Stable isotope indicators of provenance and demographics in 18th and 19th century North Americans

Abstract

Abstract Using stable isotopes to gain insight into individual life histories is a valuable tool for unidentified or incomplete remains lacking historic records. This study analyzed stable carbon, nitrogen, and oxygen isotopes from bones and teeth of 18th-19th century North Americans of known ancestry, social class, and region of origin in an effort to discern qualitative patterns and create a quantitative predictive model of demographic information. The d13Ccollagen, d13Cstructural carbonate, and d18Ostructural carbonate values provide the most overall information for detecting demographic differences, with d15Ncollagen and d18Ophosphate to a lesser degree. Region of origin was the most predictable demographic factor with 82% correct classifications based on a two-variable model using d13Ccollagen and d18Ometeoric water calculated from d18Ostructural carbonate, which reflects the influence of dominant local vegetation types and local drinking water. Ancestry was correctly identified in 68% of cases using d13Ccollagen. Social class was less predictable with correct identification in 60% of cases based on d13C, d15N, and d18O values where the upper class was most distinguishable. Isotope patterns observed in ancestry and social class groups are linked to cultural food preferences and food availability. Certain sample sites, such as military burials and urban cemeteries, show a greater range of isotope values suggesting a variety of individual regional origins and cultural backgrounds. Burials of extreme upper or lower class individuals show greater isotopic homogeneity suggesting reliance on localized food sources or cultural preferences for particular dietary choices.